OSV Woes

[hoffer]

I have a 97 540i with 180K miles. Never had any serious problems until I started getting the classic "Smoke on Startup" problem. Did lots of research on the forums that led me to the OSV.

I originally replaced the OSV without removing the intake manifold, what a pain. When I inspected the orange diaphragm, it didn't have the rips that were common with others. After the replacement was done I would hear the diaphragm vibrating, holding my hand on the back of the manifold would quiet it.

Thinking I didn't do something right the next step was to remove the intake manifold. It was full of oil. While this was out I replaced the "cyclone valve" behind the timing chain cover, the various pipes and tubing under the manifold, intake gaskets and all the o-rings that were accessible. Put it all back together and it started and ran fine, for about 2 weeks. Then another Smoke on Startup.

So now thinking I may have installed a bad OSV I replaced just the rubber diaphragm (following instructions from another thread) by popping just the cap off.

Now I have a vibrating diaphragm again and still get the frequent smoke on startup.

I'm out of ideas, any clues??

[hoffer]

An update to my previous message.

Bought an inspection mirror (mirror on a stick) and noticed the OSV diaphragm cap was not fully snapped on all the tabs. Fully seated it and the vibration is now gone. A little bit of smoke still on startup but not enough run time to tell if this was the culprit.

[witeshark]

Thanks for the update.

[brettski]

Well done. I have recently done mine as well, it wasn't until I had put it all back together that I found a seperate piece that sits over the tube on the inside face. I ended up pulling it back off to check if it was from the original or the new unit, it was from the old, but I had to be sure. There will probably be a bit of oil left in the system which should dissipate over the course of a couple of drives.

[hoffer]

I'm posting this in case someone else ends up with the same problem I did

After fully snapping the diaphram cover on, I continued to get the occasional smoke. I was checking hoses and connections for the umpteenth time and discovered the short-fat hose that connects to the back of the OSV's 90 degree elbow was loose. I was so loose I could spin it. After replacing both factory hose clamps I have been smoke free for over a month.

This vacuum leak may have been my problem all along as the original rubber diaphram was not torn and in decent shape.

[witeshark]

Good of you to follow up, thanks.

[brettski]

Well done. There are so many possible vacuum leaks on these engines.

[BBenedict]

Another thanks for the follow up.